Mn dissolution has been a long-standing, ubiquitous issue that negatively impacts the performance of Mn-based battery materials. Mn dissolution involves complex chemical and structural transformations at the electrode–electrolyte interface. The continuously evolving electrode–electrolyte interface has posed great challenges for characterizing the dynamic interfacial process and quantitatively establishing the correlation with battery performance. In this study, we visualize and quantify the temporally and spatially resolved Mn dissolution/redeposition (D/R) dynamics of electrochemically operating Mn-containing cathodes. The particle-level and electrode-level analyses reveal that the D/R dynamics is associated with distinct interfacial degradation mechanisms at different states of charge. Our results statistically differentiate the contributions of surface reconstruction and Jahn–Teller distortion to the Mn dissolution at different operating voltages. Introducing sulfonated polymers (Nafion) into composite electrodes can modulate the D/R dynamics by trapping the dissolved Mn species and rapidly establishing local Mn D/R equilibrium. This work represents an inaugural effort to pinpoint the chemical and structural transformations responsible for Mn dissolution via an operando synchrotron study and develops an effective method to regulate Mn interfacial dynamics for improving battery performance.

锰溶解是一个长期存在、普遍存在的问题，会对锰基电池材料的性能产生负面影响。锰溶解涉及电极-电解质界面处复杂的化学和结构转变。不断发展的电极-电解质界面对表征动态界面过程以及定量建立与电池性能的相关性提出了巨大的挑战。在这项研究中，我们可视化并量化了电化学操作的含锰阴极的时间和空间分辨率的锰溶解/再沉积（D/R）动力学。颗粒级和电极级分析表明，D/R 动力学与不同充电状态下不同的界面降解机制相关。我们的结果在统计上区分了表面重构和 Jahn-Teller 畸变对不同工作电压下 Mn 溶解的贡献。将磺化聚合物 (Nafion) 引入复合电极中可以通过捕获溶解的 Mn 物质并快速建立局部 Mn D/R 平衡来调节 D/R 动力学。这项工作代表了通过操作同步加速器研究查明导致锰溶解的化学和结构转变的首次努力，并开发了一种有效的方法来调节锰界面动力学以提高电池性能。